Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 419	$ 496
Other comprehensive income (loss), net of tax
Foreign currency translation adjustments	86	308
Realized and unrealized gains on derivatives	7	1
Pension and postretirement plans	(1)	(1)
Other comprehensive income	92	308
Total comprehensive income	511	804
Income attributable to noncontrolling interests	38	45
Foreign currency translation adjustments	2	36
Realized and unrealized gains on derivatives	3	0
Other comprehensive income	5	36
Comprehensive income attributable to noncontrolling interests	43	81
Comprehensive income attributable to Johnson Controls	$ 468	$ 723